This invention relates generally to bottom loading fuel tank trucks and more particularly to a socket assembly used in connection with overfill protection systems on such trucks.
Cargo tank trucks used to deliver fuel to underground storage tanks at service stations commonly have multiple fuel storage compartments. Each compartment has a manhole cover at the top thereof, a vapor recovery system, and a line communicating with the compartment for loading the compartment with fuel and unloading fuel from the compartment. Each line has a valve assembly at the end thereof to assist in the loading and unloading of fuel.
Typically, these cargo tank truck compartments are loaded from the bottom at what is known in the industry as a loading rack or island. When a fuel storage compartment is loaded from the bottom, the manhole at the top of the compartment remains closed and sealed. Due to the composition of the tank truck compartment, there is no way to visually check the rising fluid level in the compartment to make sure that an overflow does not occur. Therefore, overflow protection systems have been designed to prevent overflows or spills which may cause environmental damage, property damage due to fire and/or human injury.
The primary means used to control the amount of fuel loaded into the compartments of the tank truck are meters which are preset by the truck operator at the loading rack to dispense a predetermined amount of fuel. The pump at the loading rack stops pumping fuel into the truck""s compartment once the predetermined amount of fuel has been loaded into the appropriate compartment. Because of the human involvement in this process, errors may occur which may cause the compartment to overfill, thereby causing environmental harm and possibly injury. Such human errors include the operator entering the wrong amount to be dispensed into the truck""s compartment or the operator forgetting that some residual fuel remains in the compartment from the last delivery.
In order to reduce these human errors from causing an overfill and subsequent release of fuel into the environment, overfill protection systems have been built into cargo tank trucks. These overfill protection systems include sensing devices located in each of the fuel storage compartments on the truck. The overfill protection system on the truck, when activated, electronically communicates with a monitor at the loading rack to either close valves at the loading rack or shut off the pumps at the loading rack. When the fuel level in a compartment reaches a predetermined level, the sensing device activates the overfill protection system.
Overfill protection systems include a probe or sensor which is mounted at the top of each fuel storage compartment; a socket assembly mounted on the truck and wiring connecting each probe or sensor to the socket assembly. To activate the overfill protection system prior to the loading process, the socket assembly is electrically and mechanically connected to a plug secured at the end of a cable extending from a control monitor at the loading island by an operator. The socket assembly of the overfill protection system must meet American Petroleum Institute (API) standards.
Once the overfill protection system on the truck is electrically connected to the control monitor at the loading island via engagement of the plug with the socket assembly, the control monitor sends an electric signal through the wiring to the sensors mounted at the tops of the fuel storage compartments. If the sensors are functioning properly, a signal is sent to the control monitor on the loading island which in turn sends a signal to the pumps and the loading process occurs. If any of the sensors is wet or not functioning properly, the control monitor sends a signal to the pumps to stop loading. Since their introduction, overfill protection systems have prevented countless accidents.
The dimensional standards of the plug and socket assembly are fixed by the API. The socket assembly on each truck typically includes a plurality of electrically conductive socket pins located in a electrically insulated contact block. For purposes of this application, applicant will refer to the contact block and electrically conductive pins or contacts therein a contact block assembly. The contact block assembly is secured inside a socket. A face plate, fixedly or removably secured to the socket, is removably secured to a housing. Wires connected either to the sensors located in the tops of the tank truck compartments or to an onboard monitoring system are electrically coupled to the pins or contacts of the contact block assembly.
The outer surface of the socket has a plurality of spaced xe2x80x9cJxe2x80x9d shaped slots which are adapted to receive interlock studs located on the inside of the plug. When the operator desires to electrically connect the plug and the socket assembly to activate the overfill protection system prior to loading, the operator pushes the interlock studs on the inside of the plug into the xe2x80x9cJxe2x80x9d shaped slots of the socket and then rotates the plug. The plug and socket assembly are then electrically and physically engaged with each other so they may electronically communicate. Due to the excessive number of loadings of each tank truck, over time these xe2x80x9cJxe2x80x9d shaped slots wear and no longer are able to function properly, i. e. no longer are able to secure the plug to the socket assembly at the loading island. Consequently, the socket with the worn xe2x80x9cJxe2x80x9d shaped slots must be replaced.
In previous socket assemblies, to prevent the contact block assembly, to which the wires are attached, from being pushed rearwardly through the socket when the plug and socket assembly are engaged, the socket has an integral lip on the inner surface of a passage therethrough which abuts a shoulder on the contact block. Therefore, to remove and replace a worn socket of a socket assembly, the contact block with the wires attached must be passed forwardly through the passage in the socket. In order to remove and replace the worn socket, an operator must individually remove each of the wires from the contact block assembly. When an operator is forced to remove individual wires from the contacts of the contact block assembly, often the operator forgets which contact gets reconnected to which wire. The result is that the socket assembly is unable to be rewired, or is rewired incorrectly, thereby rendering the overfill protection system inoperative.
Therefore, there is a need for a socket assembly having a socket which may be replaced quickly and easily without an operator having to remove the wiring from the remainder of the socket assembly.
The invention of this application which accomplishes these and other objectives comprises a socket assembly adapted to be electrically coupled to sensors of an overfill protection system for use on a bottom loading fuel tanker truck. The socket assembly is configured to enable an operator to replace a worn socket without rewiring the socket assembly.
The socket assembly of the present invention comprises a housing to which is secured a face plate. Wires extending from sensors or probes located in the tops of the truck""s fuel storage compartments pass through an opening in the housing, an opening in the face plate, and are coupled to electrical contacts or pins forming part of a contact block assembly. These wires, sensors and the socket assembly of the present invention make up an overfill protection system on the tank truck. The overfill protection system is activated by an operator by engaging a plug secured to the end of a cord extending from a control monitor located on a loading island with the socket assembly of the present invention.
The socket assembly of the present invention further comprises a socket removably secured to the face plate. The socket is preferably made of electrically conductive material but may be made of any material. The socket has a passage therethrough which is sized and adapted to receive and retain a contact block assembly.
The socket has a plurality of slots on an exterior surface thereof. Although these slots are preferably xe2x80x9cJxe2x80x9d shaped, they may assume other configurations or shapes without departing from the spirit of the present invention. These slots on the socket are adapted to receive and retain a plurality of spaced interlock studs extending radially inwardly on the inside of a plug electrically coupled to the control monitor at the loading island. The location of these interlock studs and socket slots varies depending upon the type of overfill protection system utilized on any particular tank truck. When the plug is electrically and mechanically coupled to the socket assembly of the present invention, the overfill protection system is activated.
Another part of the socket assembly of the present invention is a contact block assembly which comprises a contact block made of electrically insulative material and a plurality of electrically conductive contacts. Preferably, the electrically conductive contacts are metal pins secured in holes passing through the interior of the contact block. However, the electrical contacts may be other items without departing from the spirit of the present invention. The contact block is preferably made of plastic but may be made of any electrically insulative material such as rubber.
In order to prevent the contact block assembly from being pushed rearwardly through the opening in the face plate, the contact block has a shoulder inherently built therein which abuts against the face plate. When the plug extending from the control monitor at the loading island is engaged with the socket assembly to activate the overfill protection system, the operator must push the electrical contacts on the plug into engagement with the electrical contacts of the contact block assembly of the socket assembly of the present invention. Additionally, the operator must pass the interlock studs on the plug into the slots located on the exterior of the socket and twist, thereby locking the plug and socket together.
In use, when the socket of the socket assembly becomes worn due to excessive wear, in particular the slots of the socket, the socket must be removed and replaced. In previous socket assemblies, the operator had to disconnect the wires of the overfill protection system from the socket assembly of the system before the socket could be removed and replaced. In the present invention, the socket may be removed and replaced without the operator having to remove the wires from the socket assembly.
In order to replace a worn socket using the socket assembly of the present invention, an operator first removes the face plate from the housing. The operator then removes the worn socket from the face plate by removing the fasteners which secure the face plate to the socket. The operator""s next step is to remove the contact block assembly from the inside the passage of the worn socket by removing the fastener securing the contact block assembly to the worn socket. The contact block assembly, which still has the wires secured thereto, is passed rearwardly through the passage in the worn socket so that the worn socket may be removed and replaced. The contact block assembly, with the wires attached thereto, does not pass rearwardly though the opening in the face plate during this process. Instead, the wires remain extending through the opening in the face plate.
To put the socket assembly back together without disturbing the wires of the overfill protection system, a new socket is secured to the contact block assembly. The new socket with the contact block assembly secured in the passage of the new socket is then secured to the face plate. The last step is securing the face plate to the housing. Using this process, a worn socket may be removed and replaced more easily than heretofore possible because the wires need not be separated from the socket assembly.
These and other objects and advantages of the present invention will be more readily apparent from the following drawings.